Automatic circuit-controlling system for electric elevators and the like.



N. 0. LINDSTROM. I I AUTOMATIC CIRCUIT CONTROLLING SYSTEM FOR ELECTRIC ELEVATORS AND THE LIKE.

APPLICATION FILED OUT. 18, 1911.

. 1,074,962, Patented Oct. 7, 1913.

3 SHEETS-SHEET 1. Hg: 1.

gQM MOW N. O. LINDSTROM. AUTOMATIC 013cm CONTROLLING SYSTEM FOR ELECTRIC ELEVATORS AND THE LIKE.

APPLICATION FILED OCT. 18, 1911.

Patented Oct. 7, 1913.

54 MAKE cv/Ls N. 0. LINDSTROM. AUTOMATIC CIRCUIT CONTROLLING SYSTEM FOR ELECTRIC ELEVATORS AND THE LIKE.

' APPLICATION FILED OUT. 18, 1911.

1 Q74,9 62 I Patented Oct. 7, 1913.

3 SHEETS-SHEET 8.

wi/tweooeoz 4 a 5 nos Wfoz g S511; @Hfoz 11213 UNITED srATnsrgtrEN T O NILS O. LINDSTBOM, OF NUTLEY, NEW JERSEY, ASSIGNOR T0 ALONZO B. SEE, OF NEW I YOB-K,-N. Y.

AUTOMATIC CIRCUIT-CONTROLLING SYSTEM FOR ELECTRIC ELEVATORS .A ND THE LIKE.

Specification of'letters Patent. Application flled October 18, 1911. Serial No. 855,341.

To all whom a mdyconcernr Be it known that I, NILs O. LINos'rRoM, a citizen of the United States, residing at Nut-1ev,-in the county of Essex and State of New ersey, have invented certain new and useful Improvements in Automatic Circuit- Cont-rolling Systems for Electric Elevators and the l1ke,.of which the following is a full, clear, and exact description.

This invention relates to electric elevator control systems and the like and has for one 'of its objects the rovision of automatic means in a system 0 this character for varying thecircuit conditions in accordance with the direction off-travel of the elevator car, the load thereupon, and the speed of travel of said car. i I

A further object of the herein described systemis to facilitate and simplify'the handling of an elevator car and to insure greater accuracy in stopping the car at determined points in its path of travel, especially when.

descending under heavy loads.

My novel-system is intended to, and in practice does, enable the operator to handle large motors with a more graduated automatic control than, has been hitherto possible; and in fact, to eliminate, in very large .measure, the personal equation or skill of the operator. In this connection it may be noted that the present system practically prevents, under any circumstances, a large lnrush or surge of current 0 the motor .dur-

ing the slowing down thereof as well as in the speeding up.

- These and other objects of my invention will be hereinafter described and more particularly pointed out in the claims appended hereto.

In the accompanying drawings which form a part hereof and in which like reference characters designate like parts throughout the several views: Figures 1 and 1 arerespectively the upper and lower halves ofa wiring diagram embodying the system to which this application relates. Fig. 2 is a simplified diagram of the line and dynamic-brake circuits.

Referring first to Fig. 1, adjacent the top is a positive binding post 2 and a negative post 3 by means of which current is supplied to the system.

U p and down magncts.--A circuit breaker traverses wire 6 to a post at the bottom of the board designated S1, from whence it is led by a connection 8 to a corresponding post 81 on the board of the motor. The circuit divides at 81, the bulk of the current passing through the series field 9 immediately adjacent the armature '10, and the lesser portion traversing the shunt .field coils 11 (11'), passing to said coils via post f1. The current through the series field 9 passes from terminal 82 to the series brake coils 12, via wire l3, and then flows through wire 14 to terminal SB. From thence the series field current passes along Wire'15 to post 16, where the circuit divides, one branch including the retarding or overload magnet 17, post 18, and a connection 19 to the conductive .arm 20 of the circuit breaking magnet or control 20 which .cuts out the series turns or compoundin in the manner hereinafter describe The remaining branch of this portion of the cir- 18 and a lead 23, and current flowing over Wire 22 is adapted to pass either through.

the armature 24 of a magnet 24 hereinafter Patented Oct. 7,1913.

'cuit, starting from post. 16, consists of a variable resistance 21 Which extends directly to the arm 20 above referred to.

Aconnection 22 is provided between post referred to, or the similar armature 25' of a a a contact 26 when it is intended that the elevator car shall descend; while armature 25 similarly engages contact 27, when the car is to ascend; contacts 26 and 27 being disposed at the respective extremities of the lead 23. Beneath the lead 23 is a lead 28,

at the respective, extremities of which are contacts 29v and 30, the former being adapted for engagement with the armature 31 of a magnet 31 While the latter is adapted to engage the armature 32 of a magnet 32.

The lead 28 normally delivers current to the negative side 5 of the circuit breaker from whencethe current flows via a connection 33, corresponding to connection 7, to the negative post 3 above referred to.

An inspection of the simplified wiring whether the coilsor magnets 24 and 32, or

25vand 31 are energized, said magnets being actuated in pairs, current will pass from 23 through 26 and 24 and from thence through a connection 33' to the several resistances, circuit breakers, etc., hereinafter described, returning to' lead 28 via a connection 34, corresponding to connection 33, and armature 32; or from 23' v1af27, armature 25, connection 34, etc., to 3,3: and arma;

ture 31'.

Controlling circuits.-Let us next consider the controlling or subsidiary circuits which actuate the up and down magnets 24, 25, 31, and 32 together with other devices. The lead 6 is tapped by a connection 35 which delivers current to a lead 36 which extends between a pilot magnet 37 and an actuating magnet 38, both of which latter will be considered later more particularly. A branch lead 39 extends from 36 to a fuse 40, and the latter is in turn connected via wire 41 with a pivoted contact arm 42. When this arm is disposed as shown in Fig. 1, the elevator car is at rest; but when the said arm is moved from the position marked, L so that it engages contact D, the mechanism will immediately and automatically set itself for the first or slowest speed down of the car, current passing from 42, through D to a lead 43, which is in circuit with the magnet 32. From 32, the current flows along wire 44 to magnet 24 and from thence through a connection 45 to a bindin post DR.

. For the. purpose 0 this specification, a directconnection 45 has been shown between post DR and a second post UDR, but in practice this connection would. include va-' rious devices in series which need not be herein, referred toas they, per se, form no part of the present lnvention, a slmple connection between DR and UDR- sufiicing when the system is controlled by means of the arm 42. Current leavesUDR via 46 and hereinafter referred to is in its downmost position, current will flow from V R through 4 7, contaitf48 movable contact, 49 which is fixedly secured to and in electrical communiets 524, 31, 25, .32

cationwith a contact plate50, to said plate, I

and from thence via connections 51, 52 to 3.

If contacts 48 and 49 are not properly in engagement or if resistance is introduced at such portion of the'circuit, current will flow through VR to 53 and thence directly to 52 and 3. This purpose of the arrangement of branch circuits just described isto prevent the up and down magnets 2431, etc., from acting when the core of solenoid PS above referred to is not initially disposed in its lowest position, since current through 47 encounters considerably less resistance than does'the current through 53. Toresume, therefore, the setting of the arm 42- in its D position, moves the armature 24 and.32' into their circuit closing position by the action of magnets 24 and 32 and current flows at first through both the series and shunt fields of the motor. In addition to this current is passing through both the series brake coil 12yand the shunt brake coil 54, since heeseries brake coil is, of course, in series with the series field, andcurrent reaches the shunt brake coil via arm 24' which has been drawninto engagement with contact 26, and through this arm to contact 55, lead 56, contact 57, wire 58, binding post BR, and lead 59, It passes out of the shunt winding 54 of the brake via lead 60, post BR, wire 61 fixed contact 62, movable contact 63, and fixed contact 64, wires 65 and 66, contact 67 switch arm 32, which is in engagement with contact 67, contact 30, to lead .28, and out via side 5 of the circuit breaker? A governorswitch controlled coil-\or magnet 68 operates the movable contact 63, and as this'coil is normally energized, receiving current through wires 6970, which respectively lead to series field post S2 and the usual elevator switch GS, current passing from GS via 71, the movable contact 63 is held in engagement with contact 62 and 64, completing the brake circuit just described. The particular means employed for breaking this circuit need not here be described as they form no part of the present invention.

-' Slow s eed resistances.-When the controlling e ement, in this case the arm42, is set for first or slowest speed down of the elevator car, current can pass via conductor.

mature of the motor and thereafter through lead 80, post a1, wire 81. and wire 82 to R1. The current then traverses the line resistance between R1 and LRI, and passes on overwires 83 and 84, blowout 85, to wire 34,

above referred to. Tracmgthis' portion of and 78, to thearmaturef binding post a2 I passing thence over conductor 79 to the arinmates the circuit on the diagram shown in Fig. 2, current passes from 24 to 33, to '7 5 through the resistance 86,- whi'eh corresponds to that between LR5 and R2 in Fig. 1, thence via connection 76, the motor armature, wire 80, resistance 87, which corresponds to that between R1 and LE1 abovereferred to, and out through 34, 32' and 28. As the speed in question is the lowest possible, the means for maintaining this slow speed should next be considered. Refer-ti therefore back to the point R2 from 'w ichthe line currentwas. flowing to 76-77, it will be noted that this current divides at A2, a portion flowing to the armature in the manner described and a second 'portion flowing over the I switch arm 38 of magnet 38, above referred to, to a contact- 58R, thence over wire 88, SR5, through a dynamic brake resistance, 89 to SR1, wire 90, blow out magnet 91, wire 92, contact 93, the lower end of aswitch arm 94, and thence throu h 82, to R1, etc. If therefore the speed 0 the car tends to increase, more of the line current and also more of the counter E. M. F. current from the motor, which is being driven as a generator, will pass throu h the dynamic brake resistance 89, effective y checking the tendency to race.

Second speed resistance. Considering now that the contact arm 42 has been moved to position D2, current then passes from said arm to contact D2, and from thence, for the purpose of setting forth briefly the particu-' lar invention to which this application relates, via connection 95 to post UD2. It will be seen that current may flow from this post up through wire 96, and also down through wire 97. Following that portion of the shunt going upward through 96, current will flowsuccessively through the pilot solenoid PS, wires 98, 99, 100, contact101, plate 102 (which is adapted to be carried by, but is insulated from contact '19 above referred to), contact 103, wire 104, contact 67 and out through 32'. Following the down flowing branch from UB2, current will pass over 97, and through the actuatin magnet 94 of the switch arm 9-1, above re erred to. This switch arm is normally in contact with the contact 93 above referred to, but its upper end is adapted to engage a contact lLR when its magnet 94 is energized in the manner just described. Movement of switch arm 91 to contacting posit-ion with lLR occurs therefore immediately the car controlling devices are set for second speed down. In fact this arm is the first to cut in upon establishing contacts for such speed, and the corresponding speed when ascending, and also the first to cut out upon dis-establishing such circuit conditions. It should here be stated that the circuit is constituted as described only so long as the core of the pilot solenoid has not moved upwardly to its uppermost position. When this has co I curred, contact between 102and contacts 101 .a heavy flow of current is not needed therethrough, and the resistance 105 hence acts as a cooling resistance for the solenoid coil. and also for the coil of magnet 94.

Line and dyvmmz'c brake resistance switciws.Let us next consider the effect of actuating switch arm 94. 3. Currenthad previouslybeen flowing through 80, 81, 82

and the ine resistance 87. ovement of arm 94 breaks contactat 93 and makes it as ILR. As a result the line resistance 87 is in eilect cut out of circuit, the bulk of the current flowing thercaround via arm 94-, lead 61-1, to blow out and thence "to conductor 31, etc. As the pilot solenoid has been energized as described, contact plate 50 which moves upwardly from plate 102, and is at all timcsinsulatcd therefrom, first engages the yielding contact 109; and this completes the circuit which controls magnet 38 above referred to. Current will thereforefiow downwardly through 36, as above described, through magnet 38, to wire 110; thence through'wire 111 to contact 109, plate .50, and wires 51 and 52, to 3. As plate 50 continues to rise it successively engages contacts 113, 114 and 1:15; contact 113 controlling actuating magnet 116, currentflowing from 36, through-116 and wire 117 to 113; contact 114 controlling magnet 118, current flowing from 36, through 118, 119, 119 to 11 1; and'contact 115 controlling magnet 120, current beingdrawn from wire 36, passing from 120 via 121, through point 122, lead 123, to contact .15. The successive aotuations of the magnet arms 38. 116, 'llSand 120, by moans of the corresponding magnets 38, 116. 118 and 120. effects a step'by step or -ubs-ztantially gradual raductinn o't resistance in the armature circuit, since arm 38' ctmtacts with 2Llt': arm 116 with 311R; arm 118 with 411R; and arm 120 with contact SLR; 211R beingin communication with a point LE2 in the line resistance via lead 124, 3Llt with a second point L113 in said resistance via lead 125 and 4LR with a third point LE4 of the same "ia lead 126. Thus not only is'the line of resistance 87 cutout in the manner already described, but successive parts of resistance 86 are one after another cut out, the arm 120 being the last operated and making contact with 5LR, from which a' lead, 127 extends directly to coil 74, above referred to, which is in electrical communication with the lead 75; substantially no line resistance being in circuit after the actuation of arm 120, except the series winding of the field and brake.

The conductive member 77 is, as has been stated, in communication with the armature binding post a2, via lead 78 and post A2, and when the several magnets 94, 38, 116, 118- and 120 are not energized, current flows through the lower portions of the arms corresponding to these magnets to a series of contacts respectively designated 93, 5SR, 4SR, 3SR and QSR. Con- 'tact' 93 is connected via wire 92, blowout coil 91 and lead 90 with the point SR1 of the dynamic brake resistance. Correspondingly contact 58R communicates with point SR5 in this resistance by means of lead 88, previously referred to; 4SR with point SR4 of said resistance by lead 129; 3SR with SR3 via 130; and 23B with SR2 via 131.

WVhen the successive arms 94, 38, 116', et-c., are being actuated in the manner just described, the first of these, to wit, 94, breaks at 93 the circuit which includes the entire dynamic brake resistance so that the successive actuations of arms 38, 116', 118 and 120 are, in this case, in so far as the dynamic brake is concerned, without effeet; the dynamic brake having been'entirely removed at the start, with the exception of such portion thereof as may be introduced by the action of the first automatic dynamic-brake switch, hereinafter referred to; and then only provided that here has been need for such braking action. Tn any case, however, since the rotation of switch arm 94 counter-clockwise breaks a circuit hereinafter described which controls the said first automatic switch, this possible residual braking action can only be momentary.

Shunt field re8a'stame.--When arm 94 is moved into engagement with contact lLR, current is delivered to a lead 132, from said contact, which lead extends to a magnet 133; lead 134, connecting said magnet to the wire 75, above referred to. The armature 133 of magnet 133 is adapted for engagement with a contact 135, and the pivoting stud thereof isconnected via wire 136 with the post F3, which post is in turn connected with the binding post f3 of the motor by means of a lead 137. A corresponding post f4 is connected to a post F4 via lead 138,

and this post receives current over wire 139 from the arm 140' of an electro-magnet 140. said arm bein normally in engagement with a contain 141 which is in ouses part of the shunt field, and when one or the other of these switches is open, the current flowing through the shunt field from f1 will be forced to traverse not only the low resistance turns 11, but also the high resistance turns 11, emerging via the post f2 in either case. Current leaving f2, it may here be noted, passes via 143 to post F2, and from thence over 144 and contact 30 to lead 28.

Means for matting out the compoundz'n efi'ect.Between magnets 133 and 140 is the magnet 20 above referred to, the contact making arm 20' of which is adapted for engagement with contact 143 which is directly connected to lead 6. Hence when magnet 20 is energized the series turns are cut out, current short circuiting across directly from lead 6 to lead 22 via contact 143, arm 20 and wire 19. Let, us next consider the action of this magnet 20. It cannot beenergized u/nt-il contact has been effected between 114 and plate 50, since it draws current from connection 19, the current passing from magnet 20 via wires 144, 119, 114, 50, etc. ,Again magnet 20, is opposed by the pull-lock magnet 74, which latter is not shorted until the magnet 120 has been energized. The tendency of magnet 20 to act. therefore, is variable, and depends upon the counter-clectromotive force of the motor; while the tendency of magnet 74 to act is also variable and depends on the amount of line current flowing. Assuming now that the car is ascending or descending and that it has attained a high speed resulting in a drop in current through the line. then retarding magnet 74 will not be sufiiciently strong to oppose the action of magnet 20 and the switch-arm 20 will move -to its closed position ahead of arm 120',

instead of after movement of the latter, as

would ordinarily be the case, thereby preventing possible reversal of current in the line which would oppose the shunt field current and weaken the field; which latter action might result in the-car running away. In other words, when line current is low there is no need of any compounding efiect the arm 42 be swung farther to the right into contact with D3, which corresponds with the third speed down of the car. Current passes from 42 to D3 and (again merely for the purpose of simplifying the 5 present disclosure) over connection 145 to post UD3, and from thence over 146 to magnet 140, energizing the same and causing arm 140 to break contact with 141. The current leaves magnet 140 via 147 which delivcrs into 123,- unitingv with current passing over 123 from magnet 120. i As stated, the energization of magnet 140 pulls arm 140 out of contact with 1451, thereby interrupting the short circuit about the high resistance outside turns E1 1 of the shunt field and thereby lowering the total amount of current which passes through the shunt field.- To review briefly, therefore, the ac-g 'tion cf magnets 133- and 140: When the -maare effectively in circuit with the shunt field, the field accordingly being weak. When the chine is at rest, the switch arm 133 is in} open posit-ion and the high resistance turn-s switch-arm i353 is moved to its closed posi- 1 tion, immediately contact is eflected be:

tween-211 10142 and D, these high resistanceturns are out out and the field correspondingly strengthened. When the arm 42 is moved to the highest speed position D3, switch-arm 133 remains in closed position, but switch-arm 140 opens and the field is again weakened to permit of an acceleration of, speed of the motor; arm 133 remaining closed until the motor stops,which stopping, an especially valuable feature when descending with a heavy load, since the brake need notv be wholly depended results in strong field being present at upon. The action of the hold back coils 17 switch-arm 20 in case the line current is excessive, .due to a heavy load on the motor,

until the magnet 94 has acted. The hold 45 140 and holdsihe arm 140 in its circuit closing position until the line current falls a certain amount depending on the load. In other words, if a heavy load is upon the motor, arm 20 isheld back until arm 94 has acted; then the closure of switch-arm 20 permits some current which would otherwise have passed through magnet 17 to pass therearound, weakening it, and-as the car has started to increase its speed, and as correspondingly the line current. has fallen toa determined amount, magnet 17 is so much weakened that it cannot successfully oppose magnet 14Q longer, and arm 140 then swings into its closed position. This action of switch-arm 14-0 can only occur, normally, when the operator is holdand 74 is of importance in this connection.- Ihe latter coil is adapted to hold back the I.

back coil 17 similarly opposesthe magnet either direction) since otherwise magnot 1-40 is not energized. l he variable resistance 21 is provided for the purpose of adjusting the strength of magnet 17 to suit conditions.

Speed reducing wnd stopping actz'0ns. (.ionsidering next the circuits established for the several speeds of the car when the arm 42 is withdrawn successively from D4, D2 and D. Upon swinging arm 42 away from D3 toward position L, .the circuit which energizes magnet 146) in the manner above described is, of course, broken, and arm 140' moves back into en agement with contact 141, reestablishing the short circuit about the high resistance shunt field turns 11, and the speed of the elevator car is accordingly diminished. When 42 is 'moved from D2 toward L, the first result is the deenergizavtion of magnet 94 with consequent movement of its arm-94 into the position shown in Fig. 1, by reason of the interruption of the circuit 42,1)2, 95, UD2, 97, .94, etc., previously traced, and resultin in reestablishing the dynamic brake. Si ultaneously the pilot coil or solenoid PS is also decnergized since it draws current from UD2 via 96.- The contact plate 50 accordin ly descends at moderate-speed, being provi ed with a dash-pot 148, and the several circuits controlling arms 120, 1-18, 116, and 38 are interrupted in the order named, owing to the successive separation of plate 50 from contacts 115,114,113 and 109. It will be seen, therefore, that while arm 94 takes precedence in movement overar'ms 38, 116', 118 and 120 when contact is made with D2, it also takes precedence-over these arms when contact at is interrupted. As arm 94 cuts line resistance 87 in or out and'cor- 're s'pondingly dominates the dynamic brake circuit as awhole, it is evident that the several resistancescontrolled by magnets 120, 118, 116 and 3.8 will be re-introduced into the dynamic-brake circuit successively when this circuit has been rendered operative by the movement of the switch-arm 94'. In no other words the dynamic-brake is applied gradually when the car is being'brought to slow speed or rest and the operator need not be depended upon. I therefore am enabled to automatically cut out the dynamic brake eflect substantially immediately upon starting up from slow speed and to gradually reestablish it upon slowing down or stopping. Finally when arm 42. is returned.

to L, therebybreaking the circuit which dominates magnets 24, and 32: the arms 24: and 32 move to open circuit position, current to the motor is shut off and the brakes are applied, as current ceases to flow through the brake coils.

I Operation during a-3cent.1n order to cause the car to ascend, arm 42 is first moved to U, and establishes the following circuit: 4, 6, 35, 36, 39, 4o, 41, 42, U, 150, magnet 31, 151,:magnet 25, "152, 'UR, 153 (-for :plir- .130

poses of this application) to the common return binding 25 and 31', closing the primary circuit and allowing current to flow via 6, S1, throu h the armature, series field and series bra e coils in the manner previously described, thence through SB, 15, 17, 22, 23, 27, 25', 34, 85, 84, 83, line resistance 87, wires 82, 81, postal, the armature, 02, 78,77, 76, R2, line resistance 86, 75, 74, 73, 72, 33., 31, 29, 28, 5; thus passing current through the motor armature in a direction opposite to that previously described. Upon moving arm 42 to its second-speed-up position, 2'. c. into contact with U2, current will flow from 42 to U2, and (for urposes of this application) via 154 to 2, at which pomtit divides precisely as in the preceding case, current flowing down over 97 and actuating switch-arm 94', and current flowing up over 96 and energizing the pilot solenoid PS with similar results. Upon moving 42 to U3, current may pass over 155, from U3, to the common return bindingpost UD3, whence it flows over 146, 140, etc., precisely as in the case of current delivered from D3 via 145, (previously discussed) and with similar effects.

Automatic dynamic brake switches.-- Considerin now more especially the func-- tion of t e automatic dynamic brake switches elsewhere referred to. Current for both of these is drawn from contact 4LR,

. and passes over wire 160, contacts 161, which are controlled by magnet 37, wires 162, 163, automatic magnet 164, wire 165, to contact 93; and it is hence evident that the switcharm 1644 of magnet 164, can only be actuated when switch-arm 94' disposed, as shown in Fig. 1. The automatic switch circuitbranches at 166, so that current also passes through the second automatic switch magnet'167, flowing thence via 168 to 93; the switch-arm 167' of magnet 167 hence also being dominated by switch-arm 94'. Magnet 164 is preferably set to operate at a lower potential than magnet 167, and the former will therefore operate first.-

When thepilot magnet 37 lifts, breaking circuit at 161, current to magnets 164 an 167 will be taken solely from R2, via 76 169, resistance 170, and wire 171, instead of from R2 and 4LR, givin practically the exact counter E. M. F. rom the motor throu h said resistance 170. At slow speed,.

there ore, magnets 164 and 167 receive current from the line together with the counter E. M. F. available, while upon slowing down from high speeds current for said magnets is drawn solely from the armature. This results in a savmg of current and also Lot/aces enables the use of the same strength magnets at,164, 167, as at 116, 120, etc., resultin in uniformity. v

hen magnet 164 acts the following dynamic-brake circuit is established: Current flows from the armature at 0.1 through 81, 82, R1, resistance 172, post SR6, 173, to automatic switch-arm 164, thence via contact 7 SR, blowout 174, leads 175, 76, 77,

78 to a2. Correspondingly when magnet 167 acts it short circuits apart of the permanent dynamic-brake resistance and thecurrent through the dynamic-brakecircuit flows as follows: a1, via 81, 94', 93, 92, 91,

90, SR1, resistance 176, SR8, 177, 8SR, 167,-

line wire 17.8, SR9, resistance 179, SR4, 129, 4SR, and, in case switch 116' is in its back position as shown in Fig. 1, current will flow thereover to 7 7, 78 and back to (12. If switch 116 is forward then the current flows on from SR4 through. resistance 180, to SR3, 130, 3SR, and up switch 118 to 77, etc. If

switch 118' be also in its forward position further resistance may be included in like manner until a switch is found in its back position or if none be so disposed, the current will flow through all of the dynamic brake resistance to R2 and thence out via 7 6, 77, etc.

For convenience in tracing circuits switch contacts 2SR, 3SR, 4S R, are respectively connected in the manner above described to points alon the dynamic brake resistance which have been correspondingly designated SR2, SR3 and SR4. Contact 58R similarly is electrically connected to SR5 via 88, current being received through resistance 179 which lies between posts SR5 and IOSR,

the latter being connected by a lead 180 with a post SRlO in the upper line of resistance.

An inspection of the simplified diagram shown in Fig. 2 will render more clear the relationship of the several resistances and their controllin switches.

The automatic switches 164 and 167' cannot act after switch 94 has been actuated, for reasons previously given; while switch 164 normally closes before switch 167. Switch 164 when closed affords a second path for the current through the dynamic brake circuit, said path comprising resistance 172, via 173, switch 164 and Wire-17 5. When subsequently switch 167 closes, the resistance between SR8 and SR9 is short circuited. In general therefore, in descending, if the load be exceedingly heavy and the counter E. M. F. developed by the motor, as a result, be high, the automatic switches 164' and 167 successively increase the dynamic brake action by successively decreasing resistance in the dynamic brake cir cuit, or, briefly, these automatic switches put in an automatically variable dynamic brake across the armature, depending on the load.

Action of pilot magnet.VVhen the plate 50 has been moved'into contact with 109,current flows from wi re 36 through the pilot magnet 37, wire 181, a resistance 182, wires 183, and 111 to contact 109 and thence out. If after the magnet 37 has been energized contact between 109 and 50 be broken, the magnetwill still continue to be energized, since current will flow via- 181 and a second resistance 184, 106, to 107; or to 67 via 107, 108, 66, according to the direction of motion of the car. The resistance 184 is much greater than resistance 1.82 and the current which flows through the circuit after 50 has been separated from 109 is only sufiiciently strong to hold the armature of magnet 37 in place after it has previously been lifted into its upper position by the stronger current. Now, when the machine gets up to substantially its highest speed this pilot magnet 37, lifts and breaks the short-circuit around the resistance 170 in the. automatic magnet control circuits, interrupting the flow of current tomagnets 164.-167 from 4LR. The automatic switches 16 1167 are, under these conditions, dominated solely by the counter E. M. F. from the armature, when subsequently slowing'down. In other words, these automatic switches never act at high speed, but are jointly controlled by the counter E. M. F. from the armature and by line current when the elevator is speeding up, until substantially maximum speed is attained, and by the counter E. M. F. solely when slowing down, if the latter be of sufi't cient strength.

Rcswm.It will be observed that my system comprises a plurality of automatically actuated elements and circuits which co-aet to meet the varying conditions of load and speed, encountered in practice, whether the car be ascending or descending; surging of heavy currents in the motor being prevented; while-a dynamic brake is automatically applied when required and in just the proper amounts. As a result,'the car of an elevator operated in accordance with the principles of my invention is subject to a degree of control, especially when operating under very heavy loads, which has not hitherto been attainable.

I am aware that it is possible to effect various modifications in my novel system without departing from the spirit of my invention and'I hence desire to be limited only by the scope of the claims appended hereto.

Having described my invention, I claim:

1. An electric control system comprising a motor, means to supply current thereto,

connections with said motor constituting a dynamic brake circuit, means for substantially immediately removing the dynamic brake as a Whole, and automatic means for gradually applying said dynamic brake while said motor is still adapted to receive current.

2. An electric control system comprising a motor, means to supply current thereto, connections with said motor constituting a dynamic brake circuit, said connections including a plurality of resistances, means for substantially immediately removing the dynamic brake as a Whole after starting, and automatic means for gradually applying said dynamic brake while said motor isstill adapted to receive current,said'automaticmeans including switches adapted 'to out said resistances successively out of said circuit.

3. An electric elevator control system comprising a motor, connections with said motor constituting a dynamic brake circuit, automatic means for substantially immediately removing the dynamic brake as a whole, a line resistance in circuit with said motor, said means also being adapted to cut out said line resistance from said motor circuit and automatic means for gradually applying said dynamic brake when slowing down.

- 4. An electric elevator control system comprising a motor, connections with said motor constituting a dynamic brake circuit, means for substantially immediately removing the dynamic brake as a whole, an electromagnetic appliance and connections thereto for controlling said dynamic brake removing means, a line resistance in circuit with said motor, said means also being adapted to out out said line resistance from said motor circuit, and automatic means for gradually applying said dynamic brake when slowing down.

5. An electric elevator control system comprising a. motor, connections with sa'd motor constituting a. dynamic brake circuit, means for substantially immediately removing the dynamic brake as a whole, an electro-m'agnetic appliance and connections thereto for controlling said dynamic brake removing means, a line resistance in circuit with said. motor, .said means also being adapted to cut out said line resistance from said motor circuit, automatic means for gradually applying said dynamic brake when slowing down, and means co-acting with said automatic means for gradually introducing line resistance when slowing down. I

6. An electric elevator cont-r01 system comprising a motor, connections with said mot-0r constituting a dynamic brake circuit and a line circuit,'said dynamic brake, circuit including a plurality of partial circuits with a determined resistance in each partial circuit, contact making and breakingmeans in some of said partial circuits, automatic devices for actuating said contact makin [and breaking means successively, circuit and a line circuit, each of said circuits ineluding a plurality of partial circuits with a determined resistance in each partial circuit, contact making and breaking means in some of said partial circuits, automatic devices for actuating said contact making and breaking means successively in both the dynamic brake partial circuits and the line partial circuits, circuit making and breaking means for controlling substantially the ent-ire'dynamic brake circuit, and means for energizing said automatic devices after the circuit making and breakin means for the entire dynamic circuit has een actuated.

8. An electric elevator control system comprising a motor, connections with said motor constituting a dynamic brake circuit and a line circuit, said dynamic brake circuit including a plurality of partial circuits with a determined resistance in each partial circuit, contact making and breaking means in some of said partlal circuits, automatic devices for actuating said contact making and breaking means successively, circuit making and breaking means for controlling substantially the entire dynamic brake circuit, means for actuating said last mentioned means, and cq-acting means for energizing said automatic devices'after the circuit makin and breakin means for the entire dynamic circuit has een actuated.

9. An electric elevator control system comprising a motor, connections with said motor constituting a dynamic brake circuit and a line circuit, means for cutting resistance into and out of said dynamic brake .circuit, said means including an automatic switch and an electromagnetic appliance for operating the same, said appliance normally receiving the current from the line circuit,

and an automatic controlling switch for said automatic switch.

10. An electric elevator control system comprising a motor, connections with said motor constituting a dynamic brake circuit and a line circuit, means for cutting resistance into and out of said dynamic brake circuit, said means including an automatic switch provided with an electro-magnetic appliance for operating the same, said appliance normally receiving current from both the line circuit and the dynamic brake circuit.

I1. An electric elevator control system comprising a motor, connections with said motorconstituting a dynamic brake circuit resaeea 12. An elevator control system compris-' ing a motor, connections with said motor constituting a dynamic brake circuit and a line circuit, means for cutting resistance into and out of said dynamic brake'circuit, said means including an automatic switch and an.

electro-magnetic appliance for operating the same, said appliance normally receiving current from both the line circuit and the dy-- namic. brake circuit, and automatic means for stopping the flow of line current through said-appliance when the motor is under a heavy load. 1

113. -An elevator control system comprising a motor, connections with said motor constituting a dynamic brake circuit and a line circuit, means for successively cutting resistance into and out of said dynamic brake circuit, said means including a pilot.

apparatus provided with time element means for retarding the action thereof, said auxiliary means including automatic switches rovided with elcctro-magnetic appliances or operating the same, one of .sald appliances adapted to respond to current of onestrength and another of said appliances adapted to respond to current of a greater strength.

- 14. An elevator control system comprising a motor, a conductive line leading thereto, a plurality of auxiliary switches in electrical connection with said line, line resistances dominated by said switches, dynamic brake resistance also dominated by said switches, a master switch controlling substantially all of said dynamic brake resistance, and means for actuating said master switch before said auxiliary switches.

15. An elevator control system comprising a motor having a series and shunt winding, said shunt winding including both low resistance turns and high resistance turns, means for short circuiting said high resistance turns, said means including a switch, an electro-magnetic device for controlling said switch, and an electrically operated hold-back device adapted to oppose the action of said first mentioned device, said hold-back device being in circuit with said motor.

16. In an electric elevator control system, a'motor, having a line circuit and a dynamic brake circuit, automatic means for varying said circuits in accordance with speed conditions, said means comprising a plurality of electro-magnetically operated controlling circuits for said switches, and a pilot device for successively varying said gagingsaid contacts said-rlast. mentioned means-being initially-actuable only by; a

current -o determined strength.

. 17. In an electricelevator controlsystem, a motor having a linezcircuitand a dynamic brake circuit, automatic means. for varying said circuits in accordance. withspeed conditions, said means comprising a plurality of electro magneticallyoperated switches, apilot device for successively varying said controlling circuits, said pilottdevice comprising a plurality of contacts and electrically operated means for =successively .en-

gaging-said contacts-said last mentioned. means being-initially actuable. only .by a

' current of determined strength; a branched controlling circuit 'forsaid device, and-means for varying the flow of current .throughthe branches of-said. circuitzafter said device has been actuated.

18. In an electric elevator control system, a motor having seriesiand shunt -field windings, connections with said motor constituting a line circuit and a. dynamic'brake circuit, means for cutting out the series winding when the line current is low, said means including a controlling circuit which in-v cludes an electro-magnetic device, said circuit normally drawing current from said dynamic brake circuit, and an electro-magnetic gull-back device adapted to c'o-act with said rst mentioned device to vary the action thereof, said pull-back device being normally energized by current passing through said line circuit.

19. In an electric elevator control system, a motor having series'and shunt field windings, connections with said motor constituting a line circuit and a dynamic brake circuit, a switch for cutting out the series winding, a resistance in said line. circuit, and means for cutting said resistance out of said circuit, said means adapted for actuation only after actuation of said switch when the line current is low.

20. In an electric elevator control system, a motor having series and shunt field windings, connections with said motor constituting a line circuitand a dynamic brake circuit, a switch for cutting out the series winding of said motor, an electro-magnetic device for actuating-said switch, said device connected in said dynamic brake circuit, and a second electro-magnetic device adapted to oppose action of the device first mentioned, said second device connected in said line circuit.

21. A multiple speed electric elevator control system comprising a motor having serice and shunt windings, the latter comprising low resistance and high resistance turns,

.resistance .turns. when the. system is. set for -.low-,speed, ,andrseparate automatic means .iorgcuizting ,in.:.said high resistance turns when-themotor is to be driven at a-higher speed.

comprising a motor having. series and shunt w1ndings, .the latter 1 comprising low resist- .anceand-high resistance-turns, means for cutting said .high: resistance. .turns automatically Into or out of circuit, saidmeans comprising aswitch which is normally closed .when'the. motor .is atrest, a .control ciricuit including an .electro-magneticdevice for-openingsaid switch .saidcircuit being normally. energized whenathe motor is oriveniat adetermined speed, and means for opposingthe action of said device," said means .including:an electro-magnetic device .,in.circuit with :the armature of; said motor. Z23. An electric elevator control system comprising a motor, connections thereto constituting alinecircuitand a dynamic brake circuit, said..motor. having. series and shunt windings, =the. lattercomprising low resist ance turns and a supplemental resistance adapted to be connected in series therewith, a switch for cutting out said-series winding, and means for automatically cutting said supplemental resistance out of circuit, said means being dependent in part at least upon the position of the switch aforesaid.

24. An electric elevator control system comprising a motor having connections thereto constituting a line circuit and a dynamic brake circuit, automatic electrically operated mechanism for varying said dynamic brake circuit, said mechanismineluding a plurality of electro-magnetic devices, circuits for controlling said devices and means including an' electro-magnetic pilot device for varying current conditions in said circuits, said device having a part thereof displaceable by current of a determined strength, said part being adapted to 22..An .electricelevator control system,

lot

be held in its displaced position by current of a lower strength.

25. An electric control system comprising a motor, a source of current supply therefor, means adapted to provide a plurality of speeds for said motor, a. dynamic brake circuit connected therewith, and means adapted to throw the dynamic brake into circuit with said motor upon the provision of a given speed thereto and while current is being supplied to said motor. 1

26. A motor control system comprising a motor, a source of current supply, means adapted to control the supply of current to said motor comprising a plurality of electromagnets adapted to actuate switches servin as contact makers with the main line, said switches permitting current to pass through one or more banks of line. resistautomatic means for cutting out said high arm being adapted to be thrown into and out of 'sald dynamic brake circuit ,andto thereby connect and disconnect said dynamic brake circuit from said armature upon the assumption of a given speed by said motor. p

27. A motor control system comprlsing a motor, a source of current sup ly, means adapted to control the supply 0 current to said motor comprising a plurality of electromagnets adapted to actuate-switches serving as contact makers with the main line, said switches permitting current to pass through one or more banks of line resistance and through the field of said motor, means adapted to provide a dynamic brake in connection with the armature of said motor comprising a dynamic brake circuit including therein one or more banks of resistance and a'switch-arm, said swibch-armbeing adapted to be thrown into and out of said automatic dynamic brake adapted to be thrown inupon an excessive rise of counter M. Frdeveloped by the motor.

'28; A{motor control system comprising a motor, a source of current supply therefor, a circuit leading to saidv motor from said source of current supply, banks of resistance in said circuit, a dynamic brake circuit upon the brushes ofsaid motor, banks of resistance in said dynamic brake circuit, contact members in both of said banks of resistance, and unitary switch members having elements ada ted'to contact with contacts associated wit .both of said banks of resistance.

In witness whereof, I subscribe my signature, in the presence of two witnesses.

' NILS O. LINDSTROM.

Witnesses:

WAnno M. Omrm, WILLIAM C. LAR'I. 

